Extrasolar Planets: April 2013

An international team of astronomers, including Alexandre Santerne of the EXOEarths team at CAUP, has identified and characterized two new exoplanets thanks to combined observations from the Kepler space telescope plus the SOPHIE and HARPS-N spectrographs.

Exoplanetary science has reached a historic moment. The James Webb Space Telescope will be capable of probing the atmospheres of rocky planets, and perhaps even search for biologically produced gases. However this is contingent on identifying suitable targets before the end of the mission. A race therefore, is on, to find transiting planets with the most favorable properties, in time for the launch. Here, we describe a realistic opportunity to discover extremely favorable targets - rocky planets transiting nearby brown dwarfs - using the Spitzer Space Telescope as a survey instrument.

A University of Washington astronomer is using Earth's interstellar neighbors to learn the nature of certain stars too far away to be directly measured or observed, and the planets they may host. "Characterization by proxy" is the technique used by Sarah Ballard, a post-doctoral researcher at the UW, to infer the properties of small, relatively cool stars too distant for measurement, by comparing them to closer stars that now can be directly observed.

A University of Washington astronomer, funded by a National Science Foundation (NSF) Faculty Early Career Development (CAREER) award, has discovered perhaps the smallest super-Earth planet in its host star habitable zone.

Relative sizes of Kepler habitable zone planets discovered as of 2013 April 18.
Left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth (except for Earth, these are artists' renditions). Credit: NASA/Ames/JPL-Caltech.

In our solar system, only one planet is blessed with an ocean: Earth. Our home world is a rare, blue jewel compared to the deserts of Mercury, Venus and Mars. But what if our Sun had not one but two habitable ocean worlds?

We explore the minimum distance from a host star for an exoplanet to be potentially habitable, in order to maximize future chances of finding other habitable worlds. We find that the inner edge of the Habitable Zone (HZ) for hot desert worlds is at 0.5 AU around a solar-like star (well within the orbit of Venus).

NASA will host a news briefing at 2 p.m. EDT, Thursday, April 18, to announce new discoveries from the agency's Kepler mission. The briefing will be held in the Syvertson Auditorium, Building N-201, at NASA's Ames Research Center in Moffett Field, Calif., and be broadcast live on NASA Television and on the agency's website.

In part two of The Great Exoplanet Debate, the panel of experts discuss current concepts of habitability and how these concepts are changing as our knowledge of life's potential grows. This debate comes from a plenary session hosted by Astrobiology Magazine at the 2012 Astrobiology Science Conference. The sesstion was titled: "Expanding the Habitable Zone. The Hunt for Exoplanets Now and Into the Future."

Hitherto, six P-type planets are found around five binary systems, i.e. Kepler-16 b, 34 b, 35 b, 38 b, 47 b, c, which are all Neptune or Jupiter-like planets. The stability of planets and the habitable zones are influenced by the gravitational and radiative perturbations of binary companions.

In this paper, the detectability of habitable exomoons orbiting around giant planets in M-dwarf systems using Transit Timing Variations (TTVs) and Transit Timing Durations (TDVs) with Kepler-class photometry is investigated. Light curves of systems with various configurations were simulated around M-dwarf hosts of mass 0.5 Msun and radius 0.55 Rsun.